//
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import { createContext, useContext, useEffect, useState } from "react";

type Theme = "dark" | "light";

type ThemeProviderProps = {
  children: React.ReactNode;
  defaultTheme?: Theme;
  storageKey?: string;
};

type ThemeProviderState = {
  theme: Theme;
  setTheme: (theme: Theme) => void;
};

const ThemeProviderContext = createContext<ThemeProviderState | undefined>(undefined);

function getSystemTheme(): Theme {
  if (typeof window === "undefined") return "light";
  return window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
}

export function ThemeProvider({
  children,
  defaultTheme = "light",
  storageKey = "theme"
}: ThemeProviderProps) {
  const [theme, setTheme] = useState<Theme>(defaultTheme);

  useEffect(() => {
    const storedTheme = localStorage.getItem(storageKey) as Theme;
    if (storedTheme && ["light", "dark"].includes(storedTheme)) {
      setTheme(storedTheme);
    } else {
      // No stored theme, detect system preference
      const systemTheme = getSystemTheme();
      setTheme(systemTheme);
      localStorage.setItem(storageKey, systemTheme);
    }
  }, [storageKey]);

  useEffect(() => {
    const root = document.documentElement;
    root.classList.remove("light", "dark");
    root.classList.add(theme);
  }, [theme]);

  const value = {
    theme,
    setTheme: (theme: Theme) => {
      if (typeof window !== "undefined") {
        localStorage.setItem(storageKey, theme);
      }
      setTheme(theme);
    }
  };

  return <ThemeProviderContext.Provider value={value}>{children}</ThemeProviderContext.Provider>;
}

export const useTheme = () => {
  const context = useContext(ThemeProviderContext);

  if (context === undefined) throw new Error("useTheme must be used within a ThemeProvider");

  return context;
};
